It has been reported that various spinal and paraspinal structures may be helpful in identification of LSTVs (references4-6).

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1 Diagnosis of lumbosacral transitional vertebrae on lumbar MRI: role of spinal and paraspinal anatomic markers and value of additional whole-spine localizer Poster No.: B-0899 Congress: ECR 2013 Type: Authors: Keywords: DOI: Scientific Paper N. TOKGOZ, M. Uçar, B. Erdogan Sendur, K. Kilic, C. Özcan; Ankara/TR MR, Diagnostic procedure, Congenital /ecr2013/B-0899 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 21

2 Purpose Lumbosacral transitional vertebrae (LSTVs) are common congenital anomalies. Identification of LSTVs on lumbar MRI is very important, as incorrect numbering of vertebral levels can cause wrong level surgery. It has been reported that various spinal and paraspinal structures may be helpful in identification of LSTVs (references4-6). The aim of this study is, in a larger patient group, to evaluate the value of spinal and paraspinal anatomic markers in identification of LSTVs on lumbar MRI, and to assess the need for additional whole-spine localizer (WSL) images by evaluating the diagnostic errors on lumbar MRI alone. Methods and Materials Study Population Lumbar MR examinations of 1049 adult patients (older than 16 years) with a mean age of 45.8 years (649 women, 400 men; age range, years) were studied retrospectively. MRI Technique 3.0 Tesla MR unit (Magnetom Verio; Siemens, Erlangen, Germany) with a phased array spine matrix coil was used. On lumbar MRI; T2-weighted (T2W) turbo spin echo (TSE) (TR/TE, 4000/103) and T1-weighted spin echo (500/9,7) sequences were obtained in the sagittal plane. Besides, axial T2W TSE (3000/112) images acquired parallel to the intervertebral discs were obtained. Additional sagittal WSL beginning from C2 to coccygeal levels were acquired with a combination of head, neurovascular, and spine matrix coils (Figure1). WSL was made up of 12 sagittal images of Half Fourier Acquisition Single Shot TSE (HASTE) sequence (TR/ TE, 1000/92; slice thickness/inter slice gap, 4/0.8 mm). The total acquisition time was 36 seconds. Commercially available composing software was used to create a composite image of twelve sagittal slices of the whole spine. Analysis of MR Imaging Page 2 of 21

3 Sagittal WSL was used as a gold standard in identification of vertebral levels. To evaluate the diagnostic errors in identification of the vertebral levels on routine lumbar MRI, the presence of LSTV and the level of L5 were defined on sagittal images in consensus of two radiologists blinded to the findings on WSL. The morphology of the first sacral intervertebral disc (S1-2) was characterized according to O'Driscoll et al. into one of four types (Table1) (reference11). Table 1: Classification of the first sacral intervertebral disc (S1-2) according to O'Driscoll et al [11]. Type 1 No disc material Description of the first sacral intervertebral disc (S1-2) 2 A small residual disc with an AP length less than that of the sacrum 3 A well-formed disc extending the entire AP length of the sacrum 4 A well-formed disc with the addition of squaring of the first sacral vertebra (S1) We evaluated the shapes of L5 and S1 body by measuring the end-plate ratios of each vertebra on sagittal MRI. The ratio of each vertebral body was calculated by dividing the length of superior end-plate to that of inferior end-plate. We accepted the end-plates ratio closer to 1.0 as a "rectangular shape", and the ratio more than 1.1 as a "rhombus shape" (4). We also defined the level of the longest lumbar spinous process (SP) on sagittal lumbar MRI. The locations of proximal right renal artery (RRA), root of superior mesenteric artery (RSMA), aortic bifurcation (AB) and conus medullaris (CM) were described as the level of vertebral body or intervertebral disc. Images for this section: Page 3 of 21

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5 Fig. 1: Example of sagittal WSL image with HASTE sequence for numbering lumbar vertebrae. Page 5 of 21

6 Results On WSL, 864 patients (82.4%) had normal segmentation and 185 (17.6%) had LSTVs. We found sacralization and lumbarization in 105 (10.0%) and 80 (7.6%) cases, respectively (Table2). Table 2: Vertebral segmentation characteristics of the study population on sagittal WSL images. Number of patients (%) Normal 864 (82.4%) LSTV 185 (17.6%) - Sacralization 105 (10.0%) - Lumbarization 80 (7.6%) TOTAL 1049 Diagnostic Errors in Identification of Vertebral Levels on Sagittal Lumbar MRI Alone On sagittal lumbar MRI, LSTVs were diagnosed correctly in 120 of 185 (64.9%), and misdiagnosed as having normal segmentation in 65 of 185 cases (35.1%). From a total of correctly diagnosed 120 LSTVs, L5 was defined incorrectly in 72 patients (60%). In the normal group, 11 of 864 patients (1.3%) were misdiagnosed as having LSTVs. As a result, there were diagnostic errors in 148 of 1049 patients (14.1%) (Table3). Table 3: Diagnostic errors of the sagittal lumbar MRI in identification of lumbar segmentation. Number of patients (%) Misdiagnosed LSTV/Normal segmentation 11/864 (1.3%) Misdiagnosed normal segmentation/lstv 65/185 (35.1%) Incorrect vertebral numbering/correctly diagnosed LSTV 72/120 (60.0%) DIAGNOSTIC ERRORS/STUDY GROUP 148/1049 (14.1%) Morphologic Evaluation on Lumbar MRI Page 6 of 21

7 In the normal group, there were only eight cases (0.9%) with type 3, and four cases with type 4 (0.5%) S1-2 disc configuration. In sacralization, there was no type 3 or 4 configuration. All 80 cases with lumbarization revealed a type 4 disc morphology (Figure2). The average end-plate ratios of L5 were statistically different in the normal and sacralization groups, which were 1.02 ± 0.05 vs ± 0.25, respectively. There were also statistically different average end-plate ratios of S1 in the normal and lumbalization groups, which were 1.65 ± 0.21 and 1.05 ± 0.06, respectively. L5 body showed a rhombus shape in sacralization group, and S1 body showed a rectangular shape in lumbarization group (Figures2,3). L3 had the longest SP in the normal, lumbarization and sacralization groups, in 84.3%, 97.5%, and 58.1% of the patients, respectively. There were statistical differences between these groups. Locational Distributions of the Spinal and Paraspinal Structures on Lumbar MRI In normal group; the proximal RRA was most prevalent at L1 body and L1-2 disc, in 53.6% and 34.1% of the cases, respectively (Figure4). The RSMA was most commonly located at L1 body and T12-L1 disc, in 55.1% and 31.6%, respectively (Figure5). The AB was most prevalent at L4 body in 71.1% of the patients (Figure6). The CM was variably located at L1 body, L1-2 disc, L2 body, T12-L1 disc, and T12 body, in 44.8%, 23.6%, 17.7%, 8.7%, and 3.5% of the cases, respectively (Figure7). Comparing with the normal group, the proximal RRA, RSMA, AB and CM were found to be located higher in the sacralization and lower in the lumbarization group (Figure8). The locational distributions of spinal and paraspinal anatomic markers showed statistically significant differences within and between these study (normal, sacralization and lumbalization) groups (P < 0.001). Images for this section: Page 7 of 21

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9 Fig. 1: Example of sagittal WSL image with HASTE sequence for numbering lumbar vertebrae. Page 9 of 21

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11 Fig. 2: Sagittal T2W MRI of a man shows lumbarization of S1 vertebra (thick arrow). There is a well-formed S1-2 disc (thin arrow) with of squaring of S1 vertebral body (thick arrow). Page 11 of 21

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13 Fig. 3: Sagittal T2W MRI of a woman demonstrates sacralization of L5 vertebra (arrow). L5 body shows a rhombus shape similar to S1 vertebra. Page 13 of 21

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15 Fig. 4: Sagittal T2W images of a man with normal lumbar segmentation. The proximal RRA (arrow) is located at L1-2 disc space. Page 15 of 21

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17 Fig. 5: Sagittal T2W images of a man with normal lumbar segmentation. The RSMA (arrow) is positioned at L1 body. Fig. 6: Axial T2W images of a man with normal lumbar segmentation. The AB (arrow) is located at L4 body. Page 17 of 21

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19 Fig. 7: Sagittal T2W MRI of a woman with normal lumbar segmentation shows that CM (arrow) is located at L1 body. Fig. 8: Comparison of locational distributions of spinal and paraspinal structures in the study groups. Page 19 of 21

20 Conclusion The spinal morphologic features and locations of the spinal and paraspinal anatomic structures on lumbar MRI are not completely reliable in diagnosis of LSTVs and definition of vertebral levels. Additional WSL would be useful for accurate localization of the vertebral segments on routine lumbar MRI. References 1. Huges RJ, Saifuddin A. Numbering of lumbosacral transitional vertebrae on MRI: role of the iliolumbar ligaments. AJR Am J Roentgenol 2006;187: Huges RJ, Saifuddin A. Imaging of lumbosacral transitional vertebrae. Clin Radiol 2004;59: Konin GP, Walz DM. Lumbosacral transitional vertebrae: classification, imaging findings, and clinical relevance. AJNR Am J Neuroradiol 2010;31: Lee CH, Park CM, Kim KA, et al. Identification and prediction of transitional vertebrae on imaging studies: anatomical significance of paraspinal structures. Clin Anat 2007;20: Carrino JA, Campbell PD, Lin DC, et al. Effect of spinal segment variants on numbering vertebral levels at lumbar MR imaging. Radiology 2011;259: Lee CH, Seo BK, Choi YC, et al. Using MRI to evaluate anatomic significance of aortic bifurcation, right renal artery, and conus medullaris when locating lumbar vertebral segments. AJR Am J Roentgenol 2004;182: Peh WC, Siu TH, Chan JH. Determining the lumbar vertebral segments on magnetic resonance imaging. Spine (Phila Pa 1976)1999;17: Castellvi AE, Goldstein LA, Chan DPK. Lumbosacral transitional vertebrae and their relationship with lumbar extradural defects. Spine (Phila Pa 1976) 1984;9: MacGibbon B, Farfan HF. A radiologic survey of various configurations of the lumbar spine. Spine (Phila Pa 1976)1979;4: Hahn PY, Strobel JJ, Hahn FJ. Verification of lumbosacral segments on MR images: identification of transitional vertebrae. Radiology 1992;182: O'Driscoll CM, Irwin A, Saifuddin A. Variations in morphology of the lumbosacral junction on sagittal MRI: correlation with plain radiography. Skeletal Radiol 1996;25: Byun WM, Kim JW, Lee JK. Differentiation between symptomatic and asymptomatic extraforaminal stenosis in lumbosacral transitional vertebra: role of three-dimensional magnetic resonance lumbosacral radiculography. Korean J Radiol 2012;13: Page 20 of 21

21 13. Bron JL, van Royen BJ, Wuisman PI. The clinical significance of lumbosacral transitional anomalies. Acta Orthop Belg 2007;73: Wigh RE. The thoracolumbar and lumbosacral transitional junctions. Spine (Phila Pa 1976)1980;5: Malanga GA, Cooke, PM. Segmental anomaly leading to wrong level disc surgery in cauda equina syndrome. Pain Physician 2004;7: Wigh RE. Phylogeny and the herniated disc. South Med J 1979;72: Wigh RE, Anthony HF Jr. Transitional lumbosacral discs: probability of herniation. Spine (Phila Pa 1976)1981;6: Sobottke R, Koy T, Röllinhoff M, et al. Computed tomography measurements of the lumbar spinous processes and interspinous space. Surg Radiol Anat 2010;32: Tan SH, Teo EC, Chua HC. Quantitative three-dimensional anatomy of lumbar vertebrae in Singaporean Asians. Eur Spine 2002;11: Ralston MD, Dykes TA, Applebaum BI. Verification of lumbar vertebral bodies. Radiology 1992;185: Standring S. Gray's anatomy: The anatomical basis of clinical practice. 39th ed. New York: Elsevier Churchill Livingstone, 2005: Chithriki M, Jaibaji M, Steele RD. The anatomical relationship of the aortic bifurcation to the lumbar vertebrae: a MRI study. Surg Radiol Anat 2002;24: Kumar S, Neyaz Z, Gupta A. The utility of 64 channel multidetector CT angiography for evaluating the renal vascular anatomy and possible variations. Korean J Radiol 2010;11: Standring S. Gray's anatomy: The anatomical basis of clinical practice. 39th ed. New York: Elsevier Churchill Livingstone, 2005:775. Personal Information Nil Tokgoz, MD, Associate Professor; Murat Ucar, MD, Assistant Professor; Aylin Billur Sendur, MD; Koray Kilic, MD, Assistant Professor; Cahide Ozcan, MD. Department of Radiology, Gazi University Medical School, Ankara, TURKEY. niltokgoz@yahoo.com Page 21 of 21